The German patent DE 10 2008 018 827 B4 discloses a device for producing a plasma with a piezoelectric element. The piezoelectric element is equipped with a primary and a secondary region. In this case the primary region of the piezoelectric element is driven with a low voltage and at a high frequency. As a result, the plasma is ignited by the enhancement of the field on the surface of the secondary region of the piezoelectric element. According to the invention, the plasma feed is carried out by means of a counter electrode, located at ground potential, and a gas current, which sweeps past the piezoelectric element. The gas flow allows the plasma to issue from the device.
The German published patent application DE 10 2011 006 764 A1 discloses a piezoelectric transformer with an input-side piezoelectric transducer, an output-side piezoelectric transducer with at least two phases, at least a first electrically non-conductive layer, which is disposed between the input-side piezoelectric transducer and the output-side piezoelectric transducer and which mechanically couples together the input-side piezoelectric transducer and the output-side piezoelectric transducer. Furthermore, at least a second electrically non-conductive layer is disposed between the phases of the output-side piezoelectric transducer.
The U.S. Pat. No. 5,834,882 describes the construction of a multi-layer piezoelectric transformer. A first electroactive member is mechanically coupled to the second electroactive member by means of a bonding layer, which is disposed between a first major face of the first electroactive member and a first major face of the second electroactive member. The bonding layer comprises pre-stressing means for applying compressive stress to the first and the second electroactive members in the longitudinal direction.
The German published patent application DE 10 2009 023 505 A1 discloses a circuit arrangement for a piezoelectric transformer and a method for driving a piezoelectric transformer. The circuit arrangement comprises a driver circuit, a current sensor, a control unit and an oscillator. Furthermore, the circuit arrangement comprises a pulse width modulator. The pulse width modulator is connected between the oscillator and the driver circuit. The oscillator output is connected to an input of the pulse width modulator. A modulator output of the pulse width modulator is connected to the driver signal input. Another modulator output of the pulse width modulator is connected to an additional driver signal input of the driver circuit. An output of the control unit is connected to a modulator control input of the pulse width modulator. A secondary-side voltage, which is used, for example, to trigger a flash, can be tapped at the piezoelectric transformer.
The German published patent application DE 10 2007 055 014 A1 discloses a method for igniting and maintaining a plasma in a gas chamber. The piezoelectric material protrudes into a hollow space, so that the piezoelectric material is caused to resonantly oscillate due to an external electrical excitation. The hollow space contains the gas to be ionized. The electrodes are attached to the exterior of the piezoelectric material. The method lends itself to providing a plasma light source.
The Chinese patent application CN 101259036 A discloses a micro plasma pen for removing freckles. The pen comprises a plasma head for cleaning the skin, a handle housing, a micro transducer, which is arranged in the handle housing, a power output controller and a power module. The pen can deliver a high and variable plasma power output, for which an integrated circuit or a semiconductor chip microprocessor is installed in the handle housing, where in this case the integrated circuit drives a piezoelectric transformer.
The European patent application EP 2 256 835 A2 discloses a pulse generator for a piezoelectric transformer. An output stage of the amplifier drives the piezoelectric transformer at a desired resonant frequency. Two electrodes are connected to the piezoelectric transformer. The voltage, forming at the piezoelectric transformer, is adequate enough to form a dielectric barrier discharge. The generator for the dielectric barrier discharge consists of a tube or a dish. The high voltage electrode is located, for example, in a tube at ground potential.
The German patent DE 10 2005 032 890 B4 discloses a device for producing an atmospheric pressure plasma by means of at least one piezoelectric transformer. Such a transformer is made of a piezoelectric material that is divided in the longitudinal direction into at least one excitation zone and at least one high voltage zone. According to the invention, the piezoelectric transformer has at least one opening that is designed for the gas feed and that is traversed by a gas stream, as a result of which plasma can be produced in the opening.
The German utility model DE 20 2008 008 908 U1 discloses a device for producing an atmospheric pressure plasma. A gas inflow opening, which can be connected to a gas line, and an in-feed line for supplying power to the device are both connected to a power supply device.
The Japanese patent application 2003-297295 discloses a light emitting element that comprises a piezoelectric element. The piezoelectric element is excited by means of an AC voltage.
The German published patent application DE 10 2008 063 052 A1 discloses a device for cleaning the air in a room. The device comprises a housing, in which at least one opening for the intake of ambient air and at least one outlet opening for blowing out the cleaned air are provided. In this case a device for producing plasma can be disposed in the housing in such a way that germs or unpleasant odors can be eliminated.
The article “Piezoelectric Transformers—Circuits and Applications” by C. KAUCZOR, T. SCHULTE, H. GROTSTOLLEN; 47th International Colloquium, Ilmenau University of Applied Sciences, Sep. 23 to 26, 2002. The piezoelectric transformers are a suitable alternative to conventional transformers. The driving voltage is coupled into the primary side; and on the output side (secondary side) the voltage is amplified.
The article “High Efficiency Ozone Production by a Compact Ozonizer Using Piezoelectric Transformer”, by Kenji TERANISHI, Susumu SUZUKI and Haruro ITOH, Chiba Institute of Technology, discloses that the piezoelectric transformer is held at vibration nodal points. The excitation energy is fed into a first half of the piezoelectric transformer. The second half of the piezoelectric transformer is positioned between two electrodes for the barrier discharge. Just the formation of plasma alone on the free end of the piezoelectric transformer is not provided.